Pratt & Whitney Canada’s PW610F turbofan engine will power the Eclipse 500, the two companies announced on February 19, ending nearly three months of speculation about how Eclipse would get the program moving again after it terminated its agreement with Williams to use the EJ22 engine.

Eclipse has told its customers that the revised Eclipse 500 will cruise at 375 knots (20 knots faster than the goal for the original Williams-powered airplane), and range will be 1,280 nm (20 nm less than the original). Payload will increase to 2,250 pounds (up 250 pounds). Stall speed also rises, to 67 knots from the previous maximum of 64.5 knots. Certification has slipped from a promised latest date of Dec. 31, 2004, to the first quarter of 2006. These last two items–in addition to a price increase– provide grounds for any Eclipse 500 customer to cancel and receive a full refund of deposit money. The company acknowledged that there have been some cancellations (“requests for cancellation are well under five percent of the 600 individual customer base,” Eclipse CEO Vern Raburn told AIN on February 19), but declined to reveal a number pending the March 7 deadline for canceling. The price has increased from $837,500 to $950,000 for customers with non-escrowed deposits and $975,000 for customers whose deposits remain in escrow. For new orders the price has increased to $1.175 million (June 2000 dollars). Eclipse is quoting a direct operating cost of 69 cents a mile (2000 dollars) with the new engines.

Certification of both the Eclipse 500 and its PW610F engines is slated for the first quarter of 2006, and the Albuquerque-based developer of the very light jet expects to receive the first flight-ready engines late next year. “Given where the airframe development stands now, and given the credentials of who is developing the engines, this schedule really doesn’t cause us any heartburn,” Raburn told AIN. “There’s no question it’s a teeny bit on the aggressive side, but since the beginning we have discussed this strategy with Pratt. At least three months, and ideally six months, before certification of the airplane, we need an engine that is going to behave exactly like the final certified engine when we do our performance work, so that when we’re doing takeoff and climb calibrations and single-engine work we have an engine the performance of which is not going to deviate from that of the certified engine.

“What we can’t handle is Pratt’s saying at the last minute, ‘We’re going to give you four pounds more thrust or seven pounds less thrust or change the sfc,’ and they understand this. We were on track for certifying the aircraft at the end of this year, so there isn’t too much risk on the airframe program.”

The addition of tip tanks is among the changes that accompany the switch of engines. They are there primarily to meet the FAA’s requirements for expansion volume (at least three percent of total tank volume), and Raburn noted that when the airplane takes on a full load of 1,540 pounds of fuel, only “a couple of gallons” will be in the tips. “By 10,000 feet the tip fuel will all have been burned,” he said. In terms of appearance, the Eclipse 500 tip tanks will look like “something between a Cheyenne’s and a 400-series Cessna’s,” Raburn said.

Engine Weight Unclear
When asked what the new engines will weigh, the two companies gave different indications. Raburn said, “For the installed weight of this engine, complete with pumps, starter-generator and nacelles–everything hanging on the pylon–we’re looking at 280-plus pounds per engine.” The “plus” in “280-plus” might be significant. Pratt & Whitney Canada v-p of business aviation John Wright told AIN that the uninstalled weight of the PW610F (excluding pumps, starter-generator and fire detection equipment) will be just under 270 pounds.

The PW610F, rated at 900 pounds of thrust for the Eclipse 500, will have a 14-inch fan diameter, versus 16 inches for the 1,350-pounds-thrust PW615F destined to power the Cessna Mustang. The two engines are aerodynamically similar, with similar rotational speeds, but the PW610 is smaller.

The PW610 will make its first flight (aboard P&WC’s Boeing 720 flying testbed) toward the end of next year, and before Eclipse receives any engines P&WC will have logged 50 hours of PFRT (preflight rating test) on the bench and in flight.

P&WC Canada president Allain Bellemare told AIN, “This is a market we believe in, and development of the PW610F represents a significant investment. But we expect to sell a few thousand engines in the next 10 years,” Bellemare said. The opportunity to power the Eclipse 500 came late in the year, but P&WC management clearly made a convincing case to its parent company (United Technologies) that the project was worth pursuing and funding. Bellemare emphasized his company’s long experience with small turbines in the form of the PT6 turboprop, dating back to the early 1960s.

Five Flight-test Aircraft
Five examples of the redesigned Eclipse 500 will fly between 3,000 and 3,500 hours of certification flight testing, Raburn said. In the meantime, aircraft number 100, the unpressurized prototype that flew just once on August 26 last year with Williams engines, will be fitted with a pair of Teledyne drone turbojets that happen to match the EJ22s in terms of weight and size, so that aerodynamic evaluations can resume. Raburn said it should be back in the air by the end of this month to begin 300 hours of testing. Number 101 will test a new flap configuration that extends the span of the flaps into the aileron area and under the cabin, along with a more pronounced Fowler effect.

The first PW610-powered Eclipse to fly will be number 101, an FAA-conforming aircraft fully equipped with the intended systems, including pressurization and deicing/anti-icing. Number 102 will be fully representative in avionics and autopilot, and number 103 will be assigned to aerodynamic and performance testing. These three aircraft will log 1,200 hours among them. Numbers 104 and 105 will be used for ground static testing, and “Beta aircraft” numbers 106 and 107 will each log 1,000 hours of proving flights (“way beyond conventional function and reliability testing, which, by the way, is not actually required for Part 23 certification,” noted Raburn) beginning in the summer of 2005.